The effect of two-spotted spider mite populations (Tetranychus urticae Koch) on the yield and growth parameters of the early-season apple cv. Katja was evaluated during a 3-year study. In the case of the colonisation of apple trees exceeding 1,462, 2,760 and 1,548 cumulative mite days (CMDs) in the subsequent years of research, a significant reduction of the cumulative yield (14 kg/tree) and of the cumulative trunk cross sectional area increase (5.7 cm2) was observed. No significant effect of spider mites on the average weight of the fruit was observed, while the pest affected fruit colouration. The calculated values of economic injury level were 60.5, 155.5 and 51.8 CMDs in subsequent years of the study, respectively. These values are much lower than the action threshold recommended in Poland and elaborated for the European red mite - Panonychus ulmi (Koch) on apple trees. The results suggest that the tolerance of early-season apple cultivars to T. urticae may be lower when compared to late-season varieties infested with P. ulmi; therefore, the decision to implement pest management for two-spotted spider mite should be taken at a lower infestation threshold than previously thought.
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The aim of the study was to examine the possibility of processing red-fleshed apples into cloudy juices. In a series of experiments on laboratory and semi-technological scale, the effect of enzymatic treatment of the pulp, an addition of ascorbic acid, centrifugation of the must and storage conditions on the physicochemical quality of the finished juice were investigated. The following red-fleshed apple cultivars were used: "Trinity", "Maypole", "Alex Red", and as the control: "Shampion" and "Idared" cultivars. Studies have shown that an addition of ascorbic acid during pressing, in the amount of 500-100 mg kg-1 of pulp, increased anthocyanins extraction into juice and prevented their oxidation. The enzymatic treatment of the pulp did not affect the pressing yield, and adversely affected the content of phenolic compounds and antioxidant activity. It was found that due to the rapid degradation of anthocyanins the red-fleshed apple juices should be stored at low temperatures.
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Kozak M.,Rzeszow University of Technology | Iefremova O.,Rzeszow University of Technology | Szkola J.,Rzeszow University of Technology | Sas D.,Research Institute of Horticulture in Skierniewice Journal of the Association for Information Science and Technology | Year: 2015